Antiviral 5-(substituted benzal) hydantoins

ABSTRACT

Therapeutic compositions containing a compound of the formula: ##STR1## wherein: R 1 , R 2 , and R 3  are each hydrogen, hydroxy, alkoxyf 1 to 4 carbon atoms, acyloxy of 1 to 4 carbon atoms, halo, or nitro, or R 2  and R 3  together form --OCH 2  O--; or the corresponding acylated derivatives wherein there are one or more acyl groups in the hydantoin moiety and each acyl group contains from 1 to 20 carbon atoms, and the use of said compounds to control virus infections, in particular those caused by viruses of the Picorna group.

COPENDING APPLICATION

This application is a continuation-in-part of application Ser. No.262,920, filed June 16, 1972, now abandoned.

The present invention relates to a series of 5-(substituted benzal)hydantoins and their acylated derivatives, and their use as antiviralagents. The compounds described herein have been found to beparticularly effective against viruses of the Picorna group.

The invention, in particular, relates to therapeutic compositionscontaining a compound of the formula: ##STR2## wherein:

R₁, R₂ and R₃ are each hydrogen, hydroxy, alkoxy of 1 to 4 carbon atoms,acyloxy of 1 to 4 carbon atoms, halo, or nitro, or R₂ and R₃ togetherform --OCH₂ O--; and R₄ and R₅ are each hydrogen or acyl groupscontaining from 1 to 20 carbon atoms, and the use of said compounds tocontrol virus infections, in particular those caused by viruses of thePicorna group. It will be understood that the formula I is intended toinclude geometrical isomers and mixtures thereof.

Various 5-(substituted benzal) hydantoins and their preparation havebeen described in the prior art. See for example U.S. Pat. Nos.2,605,282; 2,861,079; and 2,479,065, as well as German Patent No.1,038,050; Deulofeu and Mendivelzua, Z. physiol. Chem., 219, 233 (1933),and G. Billek, Monatsh. Chem., 92, 352 (1961).

It has now been unexpectedly and surprisingly discovered that certain5-(substituted benzal) hydantoins having the formula I exhibit in vitroand in vivo antiviral activity, especially against viruses of thePicorna group.

The present invention therefore also provides a method for controllingan infection caused by a virus of the Picorna group in a vertebratewhich comprises administering to a susceptible or infected vertebrate aneffective but non-toxic amount of a compound of the formula I or anacylated derivative thereof as defined above.

A preferred group of compounds is those compounds of the formula I ortheir acylated derivatives wherein R₁ is --OCH₃ or hydrogen, and R₂ andR₃ are --OCH₃. Especially preferred are compounds where R₁ is hydrogen,R₂ is 3'--OCH₃ and R₃ is 4'--OCH₃ ; and their acetylated and propionatedderivatives.

The therapeutic compositions of the invention comprise the hereindescribed compounds and a pharmaceutical carrier.

The compounds may be used individually or in the form of mixed isomers,both geometrical and positional, and mixed mono- and di-acylatedderivatives thereof such as obtained in a crude reaction mixture. Verysuitable mixtures of this type are the acetylated derivatives preparedby reacting a compound of the formula I with acetic anhydride with orwithout anhydrous sodium acetate, or by acetylating the compound withacetic anhydride or with an acetyl halide in a suitable dipolar aproticsolvent, such as dimethylacetamide in the presence of an organic base,e.g. pyridine.

One method for preparing the unacylated 5-(substituted benzal)hydantoins is that of E. C. Britton and H. T. Smith, U.S. Pat. No.2,861,079. Alternatively, the method described in U.S. Pat. No.2,605,282 can be used, as well as the method of Wheeler and Hoffman,American Chemical Journal, 45, 368 (1911).

In the method of E. C. Britton and H. T. Smith, the appropriatelysubstituted benzaldehyde is heated with hydantoin in the presence of amonoalkanolamine. When the reaction is complete (ca. 4 hours), thereaction mixture is acidified with dilute mineral acid, such ashydrochloric acid, cooled and filtered. The 5-(substituted benzal)hydantoin is then dried and, if desired, may be purified bycrystallization from a suitable solvent.

The unacetylated compound can also be obtained by saponification of theacetylated material prepared as described below.

The acylated derivatives of the herein described 5-(substituted benzal)hydantoins can be prepared by various routes.

We have found that the 5-(substituted benzal) hydantoins are quiteinsoluble in the usual organic solvents and this makes acetylation oracylation quite difficult. However, by using a dipolar aprotic solvent,such as dimethylacetamide or dimethylformamide, the 5-(substitutedbenzal) hydantoins can be readily dissolved and in such solution can beacylated by conventional acylating agents such as alkanoyl halides,e.g., acetyl chloride, pivaloyl chloride, palmitoyl chloride or acidanhydrides, e.g., acetic anhydride, in the presence of a base such aspyridine.

It was previously reported by Deulofeu and Mendivelzua, Z. physiol,Chem. 219, 233 (1933) that the condensation of veratraldehyde(3,4-dimethoxybenzaldehyde) with hydantoin in acetic anhydride in thepresence of fused anhydrous sodium acetate gave5-(3',4'-dimethoxybenzal) hydantoin. We have now found, however, thatthis reaction leads to the formation of a corresponding acetylatedproduct.

As mentioned hereinabove, the compounds of the present invention exhibitantiviral activity against viruses of the Picorna group. It has beenfound, however, that the degree of antiviral activity dramaticallyincreases upon acylation of the 5-(substituted benzal) hydantoins in thehydantoin moiety. Thus in the condensation of 3,4-dimethoxybenzaldehydewith hydantoin by the method of Deulofeu and Mendivelzua (loc. cit.) theacetylated-5-(3',4'-dimethoxybenzal) hydantoin was found to have agreater degree of antiviral activity than the unacetylated compound,5-(3',4'-dimethoxybenzal) hydantoin.

Similarly, the other acylated-5-(substituted benzal) hydantoins can beprepared by heating the appropriately substituted benzaldehyde and ananhydrous alkali metal alkanoate together with hydantoin and thecorresponding acid anhydride. The reaction is generally conducted at anelevated temperature until the reaction is substantially complete. Forexample, in the reaction of benzaldehydes with hydantoin in the presenceof anhydrous sodium acetate and acetic anhydride, the reaction isgenerally carried out at about 125°- 140° C. It has also been found thatpotassium bicarbonate can be used in place of the anhydrous alkali metalalkanoate with similar results being obtained. After the condensation iscomplete, the reaction mixture is cooled, usually overnight, treatedwith water and then refrigerated for several hours. The crystallineproduct is then filtered, washed with water and dried. The major portionof the product appears to be the monoacylated compound, together withsmall amounts of di-acylated compound. Where the aromatic aldehydestarting material contains phenolic hydroxylic groups, it has been foundthat these are acylated under the conditions of the reaction. Thusprotocatechualdehyde, hydantoin, anhydrous sodium acetate, and aceticanhydride gave acetylated 5-(3',4'-diacetoxybenzal) hydantoin.

As mentioned above, the acylated derivatives of the herein describedhydantoins exhibit a higher degree of antiviral activity than that ofthe unacylated compounds.

It has been found that further acylation of the acylated productobtained by the condensation of the aromatic aldehyde and hydantoin inthe presence of the alkanoate salt affords a product having greaterantiviral activity than that of the starting material. The furtheracylation is generally carried out with the appropriate acid anhydride.Thus refluxing the acetylated 5-(3', 4'-dimethoxybenzal) hydantoinobtained by the condensation of 3,4-dimethoxybenzaldehyde with hydantoinas described above, in acetic anhydride for about 5 hours gave a producthaving enhanced antiviral activity as compared to the starting material.

It has been found also that reaction of the 5-(substituted benzal)hydantoin, prepared either by the method of Britton and Smith (loc.cit.) or by saponification of the product obtained in the condensationof the aromatic aldehyde and hydantoin, in refluxing acid anhydride forseveral hours affords an acylated product having enhanced antiviralactivity.

Notwithstanding this increase in antiviral behavior, it has also beendiscovered that reaction of the 5-(substituted benzal) hydantoin withthe appropriate anhydrous alkali metal alkanoate and acid anhydrideaffords an acylated product having an even higher degree of antiviralactivity. Thus, the reaction of 5-(3',4'-dimethoxybenzal) hydantoin withanhydrous sodium acetate and acetic anhydride for about 1/2 hour at 125°-130° C (bath temperature) gave an acetylated 5-(3',4'-dimethoxybenzal)hydantoin having exceptionally good antiviral activity.

Although the reasons for this behavior is not yet definitely known, inexamining the general structural formula of the 5-(substituted benzal)hydantoins of the invention, it will be realized that the acylation canoccur in the 1- and 3- positions of the hydantoin moiety. It is believedthat the degree of antiviral activity of the hydantoins may be dependentupon the location and degree of acylation, as well as the geometricalconfiguration of the compound. For example, in the case of acetylationof 5-(3',4'-dimethoxybenzal) hydantoin carried out with refluxing aceticanhydride the crude acetylated product is separable into pure N-mono-and N,N-diacetylated derivatives. In tissue culture tests the lattershowed much greater anti-viral activity than the former which, in turn,was more active than the unacetylated compound. It will be furtherappreciated by those skilled in the art that the hydantoin moiety iscapable of keto-enol tautomerism, and consequently the acylation mayprovide some O-acylation, as well as N-acylation. All of the products ofacylation are to be considered within the scope of the presentinvention.

The presence of the double bond between the carbon atom of the hydantoinring and the α-carbon of the benzal moiety creates the possibility ofcis-trans isomerism. It will be understood that the invention embracesboth isomeric forms of the herein described 5-(substituted benzal)hydantoin compounds and of their acylated derivatives, individually, aswell as mixtures of the isomers. In the case of the acylated compoundsthe invention embraces the mono and diacylates, individually as well asin the form of mixtures.

The mixtures may be separated into the pure compounds by fractionalcrystallizations from dipolar aprotic solvents such as dimethylsulfoxideand dimethylacetamide. acetamide. For example, the mono- and di-acetatesas well as their positional and geometric isomers may be separated bythis means.

As mentioned hereinabove, the benzaldehydes used in carrying out theprocess described herein may carry various substituents, such ashydroxy, alkoxy, acyloxy, halo (viz. fluoro, chloro, and bromo), nitroand methylenedioxy. Particularly preferred substituent are alkoxy groupsof up to four carbons, in particular, methoxy groups. It has been foundthat outstanding activity against Picorna group of viruses is obtainedwith di- and tri-methoxy benzal hydantoins. Especially preferredcompounds are the 5-(3', 4'-dimethoxybenzal)- and5-(2',4',5'-trimethoxybenzal) hydantoins and their acylated derivatives.

The compounds of the present invention have been found to be highlyeffective as antiviral agents, in particular against the Picorna virusescomprising enteroviruses (poliomyelitis, coxsackie, and echo viruses),and viruses of non-human origin such as foot-and-mouth virus of cattle.The outstanding characteristics of the compounds of the presentinvention are their high degree of inhibition against the above viruses,even at concentrations below 1 μ g/ml, coupled with their low order oftoxicity.

The in vitro activity of representative compounds of the presentinvention are set forth below.

In preparing the compounds for testing, they were handled asepticallythroughout. The compounds were dissolved in a minimum amount of asuitable solvent, and the final dilutions were made up to the requiredvolume in a complete culture medium in a concentration not exceeding thepredetermined maximum non-cytotoxic levels. All materials were tested byweight, first at three concentrations, 100 - 10 - 1 μg/ml and thosewhich showed an inhibiting activity in that range were carefullyretested at several concentrations below the maximum non-cytotoxiclevel.

The cell cultures used in all primary in vitro antipicorna virusscreening tests were an established cell line of the African greenmonkey kidney (VERO), a primary cell culture of the Cercopythecus monkeykidney, or human embryonic lung diploid cells WI-38.

The cytotoxic studies were preformed on each of the compounds todetermine the level of response of the cells used to the potentiallytoxic action of the substances. Cytotoxic levels were expressed as a 50percent inhibition of the cell growth as compared to the appropriatecontrols (CTD₅₀) or as a maximal non-toxic concentration (CTD₀) whichdoes not produce any morphologically detectable inhibition of cellgrowth.

Standard batches of the viruses were made by growing the virus in anappropriate cell culture and then making a pool which was dispersed inampoules and kept frozen at -76° C until used. The titer of each viruswas determined in the cell cultures used.

The cells were grown in test tubes in a suitable medium. Immediatelybefore use the initial medium was replaced with the one which containedthe test compound in an appropriate concentration. After the virus wasadded, the infected culture was incubated at 37° C for a number of daysand the cytopathic effect of the virus observed and recorded. Theresults were read every day in all of the tubes and the destruction ofcells assessed in percentage of the cell sheet destroyed: 0-25-50-75-100percent. As controls, cells with only virus (for cytopathic effect) orwith only the compound (for cytotoxic effect) were used as well as thenormal, uninfected cells (no cytotoxic - no cytopathic effects).

Degree of a specific cytopathic effect or its inhibition was calculatedat the time when the cell virus-control tubes showed completedestruction of the cell monolayer sheet. Net difference in cytopathiceffect between treated and control tubes expressed in percentage givethe extent of the inhibitory activity of the substance. From these dataa dose-response curve was then calculated and plotted.

The TCID₅₀ represents the tissue culture infective dose of virus thatwill destroy 50 percent of the cells.

    ______________________________________                                        5-(3',4'-DIMETHOXYBENZAL) HYDANTOIN                                           Polio I, Primary Monkey Kidney Cells; 316 TCID.sub.50                         Concentraton of Compound                                                                           % Inhibition                                             ______________________________________                                        100 micrograms/ml    45                                                        50 micrograms/ml    34                                                       ______________________________________                                        ACETYLATED 5-(3',4'-DIMETHOXYBENZAL) HYDANTOIN                                (A)     Prepared according to the method of                                           Deulofeu and Mendivelzua (loc. cit.)                                          (Example 14)                                                          Polio I, Vero Cells; 316 TCID.sub.50                                          Concentration of Compound                                                                          % Inhibition                                             ______________________________________                                        10 micrograms/ml     100                                                       5 micrograms/ml     100                                                       1 micrograms/ml     100                                                       0.5 micrograms/ml   93                                                       ______________________________________                                        Coxsackie B.sub.3, Vero Cells; 173 TCID.sub.50                                Concentration of Compound                                                                          % Inhibition                                             ______________________________________                                        Concentration of Compound                                                                          % Inhibition                                             ______________________________________                                        10 micrograms/ml     100                                                       5 micrograms/ml     100                                                       1 micrograms/ml     97                                                        0.5 micrograms/ml   88                                                       ______________________________________                                        Echo 9, Vero Cells; 31.6 TCID.sub.50                                          Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        >100       > 10     10.0         100                                                              6.7          100                                                              3.3          92                                                               1.0          71                                                               0.7          42                                                               0.3          29                                                               0.1          8                                            ______________________________________                                        Echo 11, Primary Monkey Kidney Cells, 178 TCID.sub.50                         Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        >100       >100     100          100                                                              50           100                                                              25           100                                                              10           100                                                              6.7          100                                                              3.3          100                                                              1.0          68                                                               0.7          32                                                               0.3          32                                                               0.1          7                                            ______________________________________                                        (B)     Prepared by acetylation of 5-(3',4'-                                          dimethoxybenzal) hydantoin with acetic                                        anhydride.                                                            Coxsackie B.sub.3, Vero Cells; 562 TCID.sub.50                                Concentration of Compound                                                                          % Inhibition                                             ______________________________________                                        1.0 micrograms/ml    100                                                      0.5 micrograms/ml    95                                                       0.1 micrograms/ml    75                                                       0.05 micrograms/ml   50                                                       0.01 micrograms/ml   20                                                       ______________________________________                                        (C)     Prepared by acetylation of 5-(3',4'-                                          dimethoxybenzal) hydantoin with sodium                                        acetate-acetic anhydride.                                             Concentration of Compound                                                                          % Inhibition                                             ______________________________________                                        1.0 micrograms/ml    100                                                      0.5 micrograms/ml    100                                                      0.1 " 100                                                                     0.05 micrograms/ml   50                                                       0.01 micrograms/ml   25                                                       ______________________________________                                        ACETYLATED 5-(3'-METHOXY-4'-ACETOXYBENZAL) HYDANTOIN                          (Example 15)                                                                  Polio I, Vero Cells; 56.2 TCID.sub.50                                         Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        > 100      > 10     10           100                                                              5            100                                                              1            12                                                               0.5          19                                                               0.1          7                                            ______________________________________                                        Coxsackie B.sub.3, Vero Cells; 562 TCID.sub.50                                Cytotoxicity    Concentration                                                                              % Inhibition                                     CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        > 100      > 10     10           80                                                               5            60                                                               1            4                                            ______________________________________                                        ACETYLATED 5-(DENZAL) HYDRANTOIN                                                                 (Example 16)                                               Polio I, Vero Cells; 56.2 TCID.sub.50                                         Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        83         10       10           19                                                               5            0                                                                1            0                                            ______________________________________                                        Coxsackie B.sub.3, Vero Cells; 562 TCID.sub.50                                Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        83         10       10           25                                                               5            0                                                                1            0                                            ______________________________________                                        ACETYLATED 5-(2',4',5'-TRIMETHOXYBENZAL) HYDRANTOIN                           (Example 22)                                                                  Polio I, Vero Cells; 100 TCID.sub.50                                          Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                                   1        1            100                                                              0.7          93                                                               0.3          90                                                               0.1          50                                                               0.07         25                                                               0.03         0                                                                0.01         0                                            ______________________________________                                        Polio I, Vero Cells; 10 TCID.sub.50                                           Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                                   1        1            100                                                              0.7          98                                                               0.3          98                                                               0.1          54                                                               0.07         27                                                               0.03         8                                                                0.01         4                                            ______________________________________                                        Coxsackie B.sub.3, Vero Cells; 178 TCID.sub.50                                Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        >100       1        1            90                                                               0.7          88                                                               0.3          75                                                               0.1          50                                                               0.07         37                                                               0.03         12                                                               0.01         0                                            ______________________________________                                        2 Coxsackie B.sub.3, Vero Cells; 56.2 TCID.sub.50                             Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        >100       1        1            100                                                              0.7          97                                                               0.3          90                                                               0.1          50                                                               0.07         43                                                               0.03         37                                                               0.01         19                                           ______________________________________                                        ACETYLATED 5-(3',4',5'-TRIMETHOXYBENZAL)HYDANTOIN                             (Example 23)                                                                  Polio I, Vero Cells; 316 TCID.sub.50                                          Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        50         10       10           96                                                               6.7          72                                                               3.3          56                                                               1            46                                                               0.7          36                                                               0.3          14                                                               0.1          0                                            ______________________________________                                        Polio I, Vero Cells; 17.8 TCID.sub.50                                         Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        50         10       10           100                                                              6.7          95                                                               3.3          60                                                               1            56                                                               0.7          42                                                               0.3          32                                                               0.1          21                                           ______________________________________                                        Coxsackie B.sub.3, Vero Cells, 316 TCID.sub.50                                Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        50         10       10           97                                                               6.7          93                                                               3.3          88                                                               1.0          68                                                               0.7          25                                                               0.3          0                                                                0.1          0                                            ______________________________________                                        Coxsackie B.sub.3, Vero Cells; 178 TCID.sub.50                                Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              Of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        50         10       10           100                                                              6.7          100                                                              3.3          100                                                              1.0          88                                                               0.7          62                                                               0.3          25                                                               0.1          12                                           ______________________________________                                        ACETYLATED 5-(3',5'-DIMETHOXYBENZAL) HYDANTOIN                                (Example 21)                                                                  Polio I, Vero Cells; 100 TCID.sub.50                                          Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μ/ml)  (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        > 100      100      10           100                                                              5            100                                                              1            32                                                               0.5          0                                            ______________________________________                                        Polio I, Vero Cells; 10 TCID.sub.50                                           Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        >100       100      10           100                                                              5            100                                                              1            50                                                               0.5          15                                           ______________________________________                                        Coxsackie B.sub.3, Vero Cells; 316 TCID.sub.50                                Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              Of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        100        100      10            100                                                             5            100                                                              1            50                                                               0.5          25                                           ______________________________________                                        Coxsackie B.sub.3, Vero Cells; 17.8 TCID.sub.50                               Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub. 0                                                                             of Compound                                               (μg/ml) (μg/ml)                                                                             )μg/ml)   % Inhibition                                 ______________________________________                                        100        100      10           100                                                              5            99                                                               1            44                                                               0.5          21                                           ______________________________________                                        PURE N-MONOACETYLATED 5-(3'4'-DIMETHOXYBENZAL) HYDANTOIN                      Example 31                                                                    Coxsackie B.sub.3, Vero Cells; 1000 TCID.sub.50                               Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              Of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        100        10       50           25                                                               10           7                                                                5            0                                                                1            0                                            ______________________________________                                        Coxsackie B.sub.3, Vero Cells; 100 TCID.sub.50                                Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              Of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        100        10       50           56                                                               10           25                                                               5            0                                                                1            0                                            ______________________________________                                         Polio I, Vero Cells; 316 TCID.sub.50                                         Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              Of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        100        10       50           84                                                               10           7                                                                5            0                                                                1            0                                            ______________________________________                                        PURE N,N-DIACETYLATED 5-(3'4'-DIMETHOXYBENZAL) HYDANTOIN                      (Example 32)                                                                  Coxsackie B.sub.3, Vero Cells; 1000 TCID.sub.50                               Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              Of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        33         10       50           100                                                              10           100                                                              5            97                                                               1            50                                           ______________________________________                                        Coxsackie B.sub.3, Vero Cells; 100 TCID.sub.50                                Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              Of Compound                                               (μ/ml)  (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        33         10       50           100                                                              10           100                                                              5            100                                                              1            75                                           ______________________________________                                        Polio I, Vero Cells; 316 TCID.sub.50                                          Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        33         10       50           100                                                              10           100                                                              5            100                                                              1            100                                          ______________________________________                                        Polio I, Vero Cells; 56.2 TCID.sub.50                                         Cytotoxicity    Concentration                                                 CTD.sub.50 CTD.sub.0                                                                              Of Compound                                               (μg/ml) (μg/ml)                                                                             (μg/ml)   % Inhibition                                 ______________________________________                                        33         10       50           100                                                              10           100                                                              5            100                                                              1            86                                           ______________________________________                                         CYTOTOXICITY OF ACETYLATED 5-(3',4'-DIMETHOXYBENZAL)                         HYDANTOIN AGAINST VERO CELLS AND PRIMARY MONKEY                               KIDNEY CELLS                                                                  Concentration      Toxicity (%)                                               in micrograms/ml   Vero       pMK                                             ______________________________________                                        300                100        100                                             250                75         100                                             200                25         75                                              150                10         10                                              100                10         0                                               75                 10         0                                               66.7               10         0                                               50                 10         0                                               33.3               10         0                                               25                 10         0                                               10                 10         0                                               6.7                0          0                                               3.3                0          0                                               1.0                0          0                                               0.7                0          0                                               0.3                0          0                                               0.1                0          0                                               ______________________________________                                    

When acetylated 5-(3',4'-dimethoxybenzal) hydantoin (Example 14) wasinjected intraperitoneally into mice the subacute LD₅₀ during 16 days bydaily injection was 400-500 mg/kg. Oral administration showed an LD₅₀ ofgreater than 1,300 mg/kg in mice.

Acetylated 5-(3',4'-dimethoxybenzal) hydantoin (Example 14) was testedin Cynomolgus monkeys, weighing from 2-4 kg, that were infected with theMahoney strain of Polio virus, at a dosage of 25 mg/kg per day initiallyfor six days by the intraperitoneal route and thereafter subcutaneouslyfor an additional 8 days. The compound was administered in a 0.5 percentsaline solution containing a small amount of dimethylsulfoxide andemulsifier. The solution was subjected to ultrasonic irradiation inorder to disintegrate and disperse the compound throughout the solution.

The results obtained in the monkey tests and set forth in the tablebelow indicated that acetylated 5-(3',4',dimethoxybenzal) hydantoin waseffective against the Mahoney Polio virus strain in the infectedanimals.

    __________________________________________________________________________    ACETYLATED 5-(3'4'-DIMETHOXYBENZAL) HYDANTOINS                                25 mg/kg/day, i.p. or s.c.                                                    Poliovirus 2 (Mahoney), TCID.sub.50 10.sup.7.8 Cyanomolgus Monkey             CUMULATIVE MORBIDITY                                                          __________________________________________________________________________              PARALYSES  PRESENCE OF POLIOVIRUS IN RECTAL SWABS                                   Average                       HISTOPATHALOGICAL                               Day of                                                                             4th Day                                                                              8th Day                                                                             11th Day                                                                            15th Day                                                                            CHANGES AS BRAIN                Group                                                                             Treatment                                                                           No.                                                                              %  Paralysis                                                                          No. %  No.                                                                              %  No.                                                                              %  No.                                                                              %  No.     %                       __________________________________________________________________________    I   Virus +                                                                       substance                                                                           2/8                                                                              25.0                                                                             13.5  4/11                                                                             36.4                                                                             2/8                                                                              25.0                                                                             2/8                                                                              25.0                                                                             1/6                                                                              16.7                                                                             2/10    20.0                     II Virus,                                                                        only   4/11                                                                            36.4                                                                             11.0 10/12                                                                             83.3                                                                             6/8                                                                              75.0                                                                             4/9                                                                              44.4                                                                             2/5                                                                              40.0                                                                             5/11    54.5                    III substance                                                                     only  0/5                                                                              0  --   0/5 0  0/5                                                                              0  0/5                                                                              0  0/3                                                                              0  0/5     0                       __________________________________________________________________________

The compounds of the present invention formulated with a suitable liquidor solid carrier can be used to control, i.e., treat or prevent, viralinfection in vertebrates. Sterile liquid carriers may be employed whereappropriate. The routes of administration include intranasal, oral andparenteral administration. The first mode of administration can beconveniently effected by means of aerosol formulations employing thewidely-known and used propellants in a suitable dispenser. An injectiblecomposition or formulation may comprise a suspension or solution of theactive compound in a mixture of normal saline solution and apharmaceutically acceptable solvent, at a concentration of from about0.05 to 0.10 percent.

Oral administration may be in the form of tablets, pills, capsules,granules, powders, syrups and the like.

Suitable pharmaceutically acceptable solid carriers include starches,sugars, various stearates and carbonates, kaolin, talc, dicalciumphosphate, calcium sulfate, and gums. Pharmaceutically acceptable liquidcarriers include water oils and water-oil emulsions which advantageouslyinclude suitable dispersing or suspending agents such as tragacanth,alginates, dextran, methyl cellulose, polyvinylpyrrolidone, gelatin, andmixtures thereof. Suitable oils for solutions and water-oil emulsionsinclude vegetable oils such as cottonseed oil, coconut oil, peanut oiland the like. For injectable solutions the liquid carrier, e.g. normalsaline, may include a solubilizer, such as N,N-dimethylacetamide orN,N-dimethylformamide.

The compounds are administered in effective, but non-toxic dosages, forexample, about 1 to 500 mg per kg of body weight per day, preferablyabout 1- 100 mg/kg per day administered in one dose or in a series ofdoses. A dosage unit may comprise from about 1 to 500 mg. of thecompound.

The following examples are provided to describe the present invention ingreater detail; however, they should not be construed to be limitationsthereof. The melting points are in ° C.

EXAMPLE 1 5-(3',4'-Dihydroxybenzal) hydantoin

A mixture of 3,4-dihydroxybenzaldehyde (2.072 g.) and hydantoin (1.50g.) in water (15 ml) was heated to 70° to give a clear solution. To thiswas added monoethanolamine (1.38 g.) and the magnetically stirredmixture was heated (90°-92°, bath temperature) for 4 hours. Within 10minutes crystallization occurred. The product was allowed to cool toroom temperature and was stored overnight. After immersing in anice-bath, the mixture was acidified with HCl, refrigerated 5 hours,filtered, washed with cold (-10°) 1:1 methanol-water and dried. Thetitle compound was obtained as a pale brown solid: 2.776 g, m.p.300°-310°. (Trituration with hot absolute ethanol gave a pale brownsolid in ca 65% recovery, m.p. 320° decomp.)

EXAMPLE 2 5-(3'-Methoxy-4'-Hydroxybenzal) hydantoin

Vanillin (3.04 g.) and hydantoin (2.0 g.) in water (20 ml were heated onthe steam-bath for a few minutes until dissolution occurred.Ethanolamine (0174 g.) was then added and the solution heated at 85°-90°(bath temperature) for 4.5 hours. The solution deposited crystals andsolidified within 0.5 hours. Concentrated HCl (5 ml) was added, themixture was refrigerated overnight (18 hours), filtered, water washedand dried. The title compound was obtained as a yellow solid (4.18 g;93%), m.p. 266°-271° decomp.

A portion (4.122 g.) was crystallized from aqueous ethanol at -10°overnight. Weight of yellow solid: 3.420 g., m.p. 267°-271°. (T. B.Johnson and R. Bengis, J. Amer. Chem. Soc., 35, 1611 (1913) give m.p.264°-265°.)

EXAMPLE 3 5-(2'-Chlorobenzal) hydantoin

A mixture of o-chlorobenzaldehyde (2.50 g.) and hydantoin (1.78 g., 1molar ratio) was treated with water (15 ml) and heated to 70°.Monoethanolamine (1.63 g., 1.5 molar ratio) was added and the mixturewas stirred magnetically at 90°-92° (bath temperature) for 4.25 hours.The mixture was cooled in an ice-bath, acidified with concentrated HCl,refrigerated overnight, filtered, washed with water and dried at 55°/10mm. The title compound was obtained as a pinkish solid (2.63 g.), m.p.266°-270° decomp.

EXAMPLE 4 5-(4'-Nitrobenzal) hydantoin

A mixture of p-nitrobenzaldehyde (2.510 g.) and hydantoin (1.671 g., 1molar ratio) in water (15 ml) was heated to 70°. Monoethanolamine (1.53g., 1.5 molar ratio) was added and the mixture was stirred magneticallyand heated at 90°-92° (bath temperature) for 41/4 hours. The mixture wascooled in an ice-bath and acidified with HCl. After refrigerationovernight the mixture was filtered, washed with water and dried at55°/10 mm. The title compound was obtained as a brown solid (3.258 g.),m.p. 252°-253° decomp.

EXAMPLE 5 5-(3',4'-Methylenedioxybenzal) hydantoin

A mixture of 3,4-methylenedioxybenzaldehyde (2.515 g.) and hydantoin(1.668 g., 1 molar ratio) in water (15 ml) was heated to 70° andmonoethanolamine (1.40 g., 1.5 molar ratio) was added. This 2 layerliquid mixture was stirred magnetically and heated at 90°-92° (bathtemperature) for 4 hours. The title compound was obtained as a paleyellow solid (3.440 g.), m.p. 248°.

Crystallization of the crude material from dioxane gave a colorlesssolid in 90% yield, m.p. 251°-252°.

EXAMPLE 6 5-(2',5'-Dimethoxybenzal) hydantoin

A mixture of 2,5 -dimethoxybenzaldehyde (2.504 g.) and hydantoin (1.507g., 1 molar ratio) in water (15 ml) was heated to 70°. To this 2 layerliquid was added monoethanolamine (1.38 g., 1.5 molar ratio). Themixture was heated 4 hours at 90°-92° (bath temperature) with magneticstirring. The title compound was isolated in the usual manner andobtained as a yellow solid (3.288 g.), m.p. 250°-252°. Crystallizationfrom dioxane (86% recovery) gave m.p. 251°-252°.

EXAMPLE 7 5-(3',5'-Dimethoxybenzal) hydantoin

A mixture of 3,5-dimethoxybenzaldehyde (2.550 g.) and hydantoin (1.505g., 1 molar ratio) in water (15 ml) was heated to 70°. Monoethanolamine(1.38 g., 1.5 molar ratio) was added and the 2 layer liquid mixture wasmagnetically stirred at 90°-92° (bath temperature) for 4 hours.Isolation in the usual manner gave the title compound as a beige solid(2.870 g.), m.p. 285°-287°.

EXAMPLE 8 5-(2',4',5'-Trimethoxybenzal) hydantoin

A mixture of 2,4,5-trimethoxybenzaldehyde (2.503 g.) and hydantoin(1.275 g., 1 molar ratio) in water (15 ml) was heated to 70°.Monoethanolamine (1.17 g.) was added and the suspension was stirred andheated at 90°-92° (bath temperature) for 4 hours. Isolation in the usualmanner gave the title compound as a yellow solid (3.306 g.), m.p.276°-277° decomp. Crystallization from dioxane did not raise the meltingpoint.

EXAMPLE 9 5-(3',4',5'-Trimethoxybenzal) hydantoin

A mixture of 3,4,5-trimethoxybenzaldehyde (2.497 g.) and hydantoin(1.276 g., 1 molar ratio) in water (15 ml) was heated to 70°.Monoethanolamine (1.17 g., 1.5 molar ratio) was added, followed bymagnetic stirring and heating (90°-92°, bath temperature) for 4 hours.Usual workup gave the title compound as a yellow solid (2.950 g.), m.p.266°-268°. Crystallization from dioxane (80% recovery) gave m.p.268°-270°.

EXAMPLE 10 5-(2'-Methoxybenzal) hydantoin

A mixture of o-methoxybenzaldehyde (2.00 g., 14.7 mmoles) and hydantoin(1.47 g., 1 molar ratio) in water (12ml) was heated to 70°;monoethanolamine (1.35 g., 1.5 molar ratio) was then added. The mixturewas heated in an oil bath (90°-92°) and stirred magnetically for 4hours. Usual workup gave the title compound as an orange solid (2.90g.), m.p. 174°-179° .

EXAMPLE 11 5-(3'-Methoxybenzal) hydantoin

A mixture of m-methoxybenzaldehyde (2.00 g., 14.7 mmoles) and hydantoin(1.47 g.) in water (12 ml) was heated to 70°; monoethanolamine (1.35 g.,1.5 molar ratio) was then added and the mixture was heated in an oilbath at 90°-92° for 4 hours with magnetic stirring. Isolation in theusual manner gave the title compound as a beige solid (2.56 g.), m.p.229°-231° .

EXAMPLE 12 5-(4'-Methoxybenzal) hydantoin

A mixture of p-methoxybenzaldehyde (2.00 g., 14.7 mmoles) and hydantoin(1.47 g., 1 molar ratio) in water (12 ml) was heated to 70°;monoethanolamine (1.35 g., 1.5 molar ratio) was then added. The mixturewas stirred magnetically and heated in an oil bath at 90°-92° for 4hours. Usual workup furnished the title compound as a pale yellow solid(2.74 g.), m.p. 250°-252° .

EXAMPLE 13 5-(3',4'-Dimethoxybenzal) hydantoin

A magnetically stirred mixture of veratraldehyde (9.00 g., 93% pure),hydantoin (5.00 g.), fused, anhydrous sodium acetate (10 g.) and glacialacetic acid (20 ml) was refluxed (bath temperature 160°-165°) for 1.5hours (solution within 5 minutes, crystallization during heatingperiod). On cooling, water was added. The mixture was stirred for 1hour, refrigerated 2 hours, filtered, washed with water and driedovernight at 55°/10 mm. The title compound was obtained as a yellowsolid: 4.72 g. (38% yield) m.p. 280°-282° .

EXAMPLE 14 Acetylated 5-(3',4',-Dimethoxybenzal) hydantoin

A mixture of pure 3,4-dimethoxybenzaldehyde (4.20 g; 99.9% pure by vpc),hydantoin (2.80 g.), potassium bicarbonate (3.20 g.) and aceticanhydride (10 ml) was stirred magnetically and heated in an oil-bath at130°-140° (both temperature) for 30 minutes. After allowing the solutionto stand overnight (during which time crystallization occurred) water(100 ml) was added, over 30 minutes, with stirring. The product wasisolated by filtration, washed with hot water (250 ml) and driedovernight at 50°/10 mm. Wt. of yellow solid: 3.90 g., m.p. 183°-218°.Acetyl value: 15.5 (theoretical for monoacetylation is 14.8).

A similar result was obtained when fused anhydrous sodium acetate wasused in place of potassium bicarbonate.

EXAMPLE 15 Acetylated 5-(3'-methoxy-4'-acetoxybenzal) hydantoin

A mixture of vanillin (1.900 g.), hydantoin (1.4 g.) and fused anhydroussodium acetate (1.3 g.) in acetic anhydride (5 ml) was heated under areflux condenser at 125°-130° (bath temperature) with magnetic stirringfor 30 minutes. On standing overnight, the solution solidifiedcompletely. Water (50 ml) was added and the mixture was stirred at roomtemperature for about one hour, then refrigerated 5 hours, filtered,washed with boiling water (ca. 200 ml) and dried at 50°/10 mm overnight(18 hours). The crude title compound was obtained as yellow solid: 2.950g. (86% yield) m.p. 188°-191° .

EXAMPLE 16 Acetylated 5-benzalhydantoin

A magnetically stirred mixture of benzaldehyde (2.60 g.), hydantoin(2.80 g.), fused anhydrous sodium acetate (2.60 g.) and acetic anhydride(10 ml) was heated at 125°-135° (bath temperature) under a refluxcondenser for 30 minutes. Dissolution and crystallization occurredduring this time. On gradual cooling to room temperature (1.5 hours),water was added, the mixture was refrigerated overnight (18 hours),filtered, washed with hot water (150 ml) and with light petroleum ether.The product was dried 50°/10 mm for 24 hours. The title compound wasobtained as a beige solid: 4.76 g., m.p. 214°-217° .

EXAMPLE 17 Acetylated-5-(2'-methoxybenzal) hydantoin

A mixture of o-methoxybenzaldehyde (2.58 g.), hydantoin (1.95 g.),fused, anhydrous sodium acetate (1.95 g.) and acetic anhydride (7.5 ml)was stirred magnetically and heated in an oil bath (125°-130°) for 30minutes (solution after 2 minutes). The mixture was removed from thebath and kept at room temperature (crystallization on coolingovernight). Water was then added, followed by refrigeration for 6 hours.The crystals were filtered off, washed with hot water and dried at55°/10 mm. the title compound was obtained as a yellow solid (3.80 g.).

EXAMPLE 18 Acetylated 5-(3'-methoxybenzal) hydantoin

A mixture of m-methoxybenzaldehyde (2.58 g.), hydantoin (1.95 g.),fused, anhydrous sodium acetate (1.95 g.) and acetic anhydride (7.5 ml)was stirred magnetically and heated in an oil bath at 125°-130° for 30minutes, (solution within 10 minutes, crystallization on cooling). Themixture was kept at room temperature overnight, treated with water,refrigerated 6 hours, filtered, washed with hot water and dried. Thetitle compound was obtained as a pale yellow solid (4.12 g.).

EXAMPLE 19 Acetylated 5-(4'-methoxybenzal) hydantoin

A mixture of p-methoxybenzaldehyde (2.58 g.), hydantoin (1.95 g.),fused, anhydrous sodium acetate (1.95 g.) and acetic anhydride (7.5 ml)was stirred magnetically and heated in an oil bath at 125°-130° for 30minutes. The mixture was stored at room temperature overnight, treatedwith water, refrigerated for 6 hours, filtered, washed with hot waterand dried. The title compound was obtained as a pale yellow solid (3.61g.) m.p. 218°-223° decomp.

EXAMPLE 20 Acetylated 5-(2',5'-dimethoxybenzal) hydantoin

A mixture of 2,5-dimethoxybenzaldehyde (2.10 g.), hydantoin (1.40 g.)and fused, anhydrous sodium acetate (1.30 g.) in acetic anhydride (5 ml)was heated at 125°-130° (bath temperature) for 30 minutes with magneticstirring (solution within 10 minutes). During overnight standing at roomtemperature, solidification occurred. Water (15-20 ml) was added and themixture was stirred 1-1.5 hours. More water (60-70 ml) was addedfollowed by refrigeration overnight. The product was filtered, washedwith hot water (ca. 150 ml). The title compound was obtained as a tackysolid (3.35 g.).

The crude material (2.893 g.) was crystallized from acetic acid to givea yellow solid (1.977 g.).

EXAMPLE 21 Acetylated 5-(3',5'-dimethoxybenzal) hydantoin

A mixture of 3,5-dimethoxybenzaldehyde (2.10 g.), hydantoin (1.40 g.)and fused, anhydrous sodium acetate (1.30 g.) in acetic anhydride (5 ml)was heated, with magnetic stirring, at 125°-130° (bath temperature) for30 minutes. After standing at room temperature overnight(crystallization), water (15-20 ml) was added, the mixture was stirredfor 1-1.5 hours and then diluted with more water (60-70 ml) followed byrefrigeration overnight. The mixture was filtered, washed with water anddried. The title compound was obtained as a pale yellow solid (3.24 g.).

EXAMPLE 22 Acetylated 5-(2',4',5'-trimethoxybenzal) hydantoin

A mixture of 2,4,5-trimethoxybenzaldehyde (2.10 g.), hydantoin (1.40 g.)and fused, anhydrous sodium acetate (1.30 g.) in acetic anhydride (5 ml)was magnetically stirred and heated at 125°-130° (bath temperature) for30 minutes. During storing at room temperature, solidification tookplace. Water (15-20 ml) was added, the mixture was stirred 1-1.5 hours,followed by addition of more water (60-70 ml), and refrigerationovernight. The product was filtered, washed with hot water and dried 20hours, 50°/10 mm. The title compound was obtained as a yellow solid(2.417 g.).

EXAMPLE 23 Acetylated 5-(3',4',5'-trimethoxybenzal) hydantoin

A mixture of 3,4,5-trimethoxybenzaldehyde (2.10 g.), hydantoin (1.40 g.)and fused, anhydrous sodium acetate (1.30 g.) in acetic anhydride (5 ml)was heated at 125°-130° (bath temperature) for 30 minutes with magneticstirring (solution after 5 minutes). During storage at room temperatureovernight solidification took place. Water (15-20 ml) was added, themixture was stirred 1-1.5 hours, followed by more water addition (60-70ml). After refrigeration overnight, the crystals were filtered off,washed with hot water (˜150 ml) and dried 20 hours, 50°/10 mm. The titlecompound was obtained as a yellow solid (2.60 g.), m.p. 185°-195°.Crystallization from acetic acid gave the product in 81% yield, m.p.190°-201° .

EXAMPLE 24 Acetylated 5-(3',4'-methylenedioxybenzal) hydantoin

A mixture of piperonal (2.199 g.), hydantoin (1.60 g.) and fused,anhydrous sodium acetate (1.50 g.) in acetic anhydride (5 ml) wasstirred magnetically and heated in an oil bath at 130 ± 2° (bathtemperature) for 30 minutes, (solution and crystallization within 5minutes). After keeping the product at room temperature for 16 hours,water was added and the mixture was stirred for 0.5 hours followed byaddition of more water and refrigeration for 6.5 hours. The mixture wasfiltered, the residue washed with hot water (150 ml) and dried 20 hoursat 50° /10mm. The title compound was obtained as a yellow solid (3.105g.), m.p. 260° -262° decomp.

EXAMPLE 25 Acetylated 5-(3',4'-diacetoxybenzal) hydantoin

A mixture of protocatechualdehyde (2.50 g.), hydantoin (2.50 g.) andfused, anhydrous sodium acetate (1.25 g.) in acetic anhydride (12.5 ml)was stirred magnetically and heated at 105° -110° (bath temperature) for0.75 hours (solution within 10 minutes). Water (12.5 ml) was added tothe hot solution and the precipitating mixture was refrigeratedovernight, filtered, water washed and dried 5 hours at 55° /10 mm. Thetitle compound was obtained as a colorless solid (1.64 g.), m.p. 200°-210° .

A portion (0.958 g.) of the latter compound was crystallized from aceticacid at room temperature. Weight of colorless solid: 0.703 g., m.p. 233°-239° .

EXAMPLE 26 Acetylated 5-(2'-chlorobenzal) hydantoin

A mixture of o-chlorobenzaldehyde (2.10 g.), hydantoin (1.80 g.) andfused, anhydrous sodium acetate (1.50 g.) in acetic anhydride (5 ml) washeated at 125° -130° (oil bath temperature) for 30 minutes with magneticstirring (solution after 5 minutes). On cooling to room temperaturesolidification took place. The mixture was left at room temperatureovernight, treated with water (ca. 25 ml), stirred for 1-1.5 hours andrefrigerated 5 hours. The solid filtered off, washed with hot water anddried 18 hours at 55° /10 mm. The title compound was obtained as ayellow solid (3.61 g.).

EXAMPLE 27 Acetylated 5-(4'-nitrobenzal) hydantoin

A mixture of p-nitrobenzaldehyde (2.00 g.), hydantoin (1.40 g.) andfused, anhydrous sodium acetate (1.30 g.) in acetic anhydride (5 ml) wasstirred magnetically and heated at 125° -130° (bath temperature) for 30minutes (solution within 5 minutes). On cooling to room temperaturesolidification took place. The material was left overnight, treated withwater (ca. 25 ml) and stirred for 1.5 hours. More water (ca. 75 ml) wasadded followed by refrigeration for 40 hours. Filtration of the somewhatsticky solid, washing with hot water (ca. 50 ml) and drying at 50° /10mm over the weekend afforded the title compound as a brown solid (3.59g.), m.p. >300° .

EXAMPLE 28 Propionylated 5-(3',4'-dimethoxybenzal) hydantoin

A mixture of pure veratraldehyde (2.10 g., 99.98% pure, by VPC),hydantoin (1.40 g.) and potassium bicarbonate (1.60 g.) in propionicanhydride (6 ml) was magnetically stirred and heated in an oil bath at125° -130° (bath temperature) for 30 minutes (clear solution after 5minutes, then gradual crystallization). The mixture was then left atroom temperature overnight (20 hours). Water was added, followed bymagnetic stirring for 45 minutes to decompose residual anhydride. Themixture was refrigerated for 8.5 hours, filtered, washed with hot water(25- 35 ml) and dried overnight at 55° /10 mm. The crude title compoundwas obtained as a yellow solid (3.07 g.). Substantially the same resultsare obtained when the benzaldehydes described in the preceding examplesare similarly treated.

EXAMPLE 29 Mono- and Diacetylation of 5-(3',4'-dimethoxybenzal)hydantoin

A mixture of 5-(3',4'-dimethoxybenzal) hydantoin (1.00 g., m.p. 280°-281° ) and acetic anhydride (10 ml) was refluxed at 150 ± 5° (bathtemperature) for 6 hours (crystallization on cooling). The mixture wasrefrigerated over the weekend, filtered and the solid dried overnight at50° /10 mm. Weight of yellow solid (0.416 g.), m.p. 204° -208° C. Aportion (0.375 g.) of the latter solid was crystallized from glacialacetic acid to give 0.298 g., m.p. 207° -211° . Acetyl value 16.1.(Theoretical for monoacetylation: 14.8%).

The filtrate from the above first crop (0.416 g.) was treated with water(precipitation) and refrigerated. The precipitated solid was filteredand dried at 50° /10 mm. Weight of yellow solid: 0.530 g., m.p. 152°-154° . Crystallization from glacial acetic acid (76% recovery) gavem.p. 150° -155° . Acetyl value: 22.0. (Theoretical for diacetylation:25.9%).

When the reaction time was extended to 16 hours, similar results wereobtained.

EXAMPLE 30 Acetylation of 5-(3',4'-dimethoxybenzal) hydantoin withsodium acetate - acetic anhydride

A mixture of 5-(3',4'-dimethoxybenzal) hydantoin (1.04 g.), prepared bysodium hydroxide hydrolysis of product described in Example 14, andfused anhydrous sodium acetate (0.44 g.) in acetic anhydride (6 ml) washeated with magnetic stirring at 125° -130° C (bath temperature) forabout 30 minutes. After storage at room temperature overnight, duringwhich time crystallization had taken place, water was added. Isolationof the product by filtration gave a yellow solid (1.49 g.). The productwas crystallized from acetic acid to give a crystalline yellow solid(acetyl value 15.1%). This product is highly effective against Picornagroup of viruses.

Substantially the same results are obtained when the 5-(substitutedbenzal) hydantoins in the preceding examples are similarly treated.

EXAMPLE 31 Preparation of pure N-monoacetylated5-(3',4'-dimethoxybenzal) hydantoin

Crude N-monoacetylated 5-(3',4'-dimethoxybenzal) hydantoin (110 g.),prepared as described in Example 29, was dissolved in dimethylsulfoxide(180 ml) by heating to 90° . Crystallization occurred on standingovernight. The crystals were filtered off and dried to give 92.8 g. ofproduct. This was recrystallized from dimethylsulfoxide (150 ml) undersimilar conditions, the crystals were filtered off, washed with ethanoland dried. The product was finely ground, slurried with ethanol (250ml), filtered, and dried to yield 77.7 g. of the pure monoacetylatedderivative, m.p. 223° -225° . N.M.R. showed the presence of one acetylgroup per molecule.

EXAMPLE 32 Preparation of pure N,N-diacetylated5-(3',4'-dimethoxybenzal) hydantoin

The filtrate as obtained in Example 29, containing the N,N-diacetylated5-(3'4'-dimethoxybenzal) hydantoin, was evaporated to dryness and theresidue (128 g.) was dissolved in dimethylacetamide (250 ml) by heatingto 100° . Overnight crystallization yielded 69 g. of product which wasrecrystallized from dimethylacetamide (100 ml) under similar conditions.The dried crystals (55.1 g.) had m.p. 181° -183° . N.M.R. showed thepresence of two acetyl groups per molecule.

EXAMPLE 33 Separation of Pure N Mono- and N,N Di-acetylated5-(3'4'-dimethoxybenzal) hydantoin and isomers

The crude reaction product, derived from the acetylation of5-(3',4'-dimethoxybenzal) hydantoin with fused anhydrous sodium acetateand acetic anhydride as described in Example 30, was crystallizedfractionally from dimethylsulfoxide. The fractions then wererecrystallized repeatedly from dimethylsulfoxide to yield the followingfive compounds:

a. N-Monoacetylated Compound A

This compound had m.p. 254° -256° . N.M.R. showed the presence of oneacetyl group per molecule.

b. N-Monoacetylated Compound B

This compound had m.p. 221° -224° . N.M.R. showed the presence of oneacetyl group per molecule.

c. N-Monoacetylated Compound C

This compound was identical with that described in Example 31.

d. N,N-Diacetylated Compound D

This compound had m.p. 134° -137° . N.M.R. showed the presence of twoacetyl groups per molecule.

e. N,N-Diacetylated Compound E

This compound was identical with that described in Example 32.

EXAMPLE 34 Preparation of pure N-mono- and N,N-di-acetylated5-(2',4',5'-Trimethoxybenzal) hydantoin and isomers thereof

5-(2',4',5'-Trimethoxybenzal) hydantoin, prepared as described inExample 8, was acetylated with refluxing acetic anhydride in the manneroutlined in Example 29. Fractional crystallization of the crude reactionproduct from dipolar aprotic solvents such as dimethylsulfoxide anddimethylacetamide provided four purified compounds:

a. N-monoacetylated Compound A

This compound had m.p. 195° -197° after several recrystallizations fromdimethylsulfoxide. N.M.R. showed the presence of one acetyl group permolecule.

b. N-monoacetylated Compound B

This compound had m.p. 223° -226° after recrystallization fromdimethylacetamide. N.M.R. showed the presence of one acetyl group permolecule.

c. N-N-diacetylated Compound C

This compound had m.p. 187° -189° after crystallizations first fromdimethylsulfoxide and then from dimethylacetamide. N.M.R. showed thepresence of two acetyl groups per molecule.

d. N,N-diacetylated Compound D

This compound had m.p. 175° -177° after recrystallization fromdimethylacetamide. N.M.R. showed the presence of two acetyl groups inthis molecule.

EXAMPLE 35 Acetylation of 5-(3',4'-Dimethoxybenzal) hydantoin inDimethylacetamide-Pyridine

A solution of the above mentioned hydantoin (0.5 g.) in anhydrousdimethylacetamide (5 ml) and anhydrous pyridine (0.6 ml) was treatedwith acetyl chloride (0.5 ml), when there was immediate precipitation ofa yellow solid, with slight evolution of heat. After allowing themixture to stand at room temperature overnight (17 hours), the product(0.53 g.) m.p. 204° -208° C was isolated as a yellow solid byprecipitation into water. Crystallization from dimethylsulfoxide asdescribed in Example 31 gave yellow crystals (0.170 g.), showingidentical N.M.R. spectrum to that of the monoacetylated5-(3',4'-dimethoxybenzal) hydantoin described in Example 31.

EXAMPLE 36 Pivaloylation of 5-(3',4'-Dimethoxybenzal) hydantoin

To a solution of the hydantoin (0.5 g.) in dimethylacetamide (5 ml) andanhydrous pyridine (2 ml), pivaloyl chloride (2 ml) was added and theresultant pale yellow solution left at room temperature over the weekend(67 hours). The solution was poured into water, extracted with methylenechloride and the methylene chloride extract washed once with NaHCO₃solution, then with dilute hydrochloric acid and finally with water.Evaporation of the dried (Na₂ SO₄) extract left a yellow solid (0.5 g.),m.p. 153° -158° . Crystallization from methylene chloride-lightpetroleum (bp 30° -60° C) gave the mono-pivalylated derivative as yellowcrystals (0.27 g.), m.p. 177° -178° .

EXAMPLE 37 Palmitoylation of 5-(3',4'-Dimethoxybenzal) hydantoin

To a solution of the above mentioned hydantoin (0.5 g) in drydimethylacetamide (5 ml) and anhydrous pyridine (1.0 ml) palmitoylchloride (2.75 g) was added, resulting in formation of a yellowprecipitate. After allowing the mixture to stand at room temperature for64 hours water was added and the resultant solid was filtered off andwashed first with water and then repeatedly with hexane. The resultingbeige solid (1.5 g), m.p. 75° -78° was crystallized from a mixture ofchloroform and light petroleum to give the dipalmitoylated derivative asa nearly colorless solid (0.9 g) m.p. 87° -88° .

The term "vertebrate" as used herein is intended to include mammals andbirds, both of which are subject to infection with viruses of thePicorna group.

We claim:
 1. A therapeutic composition in dosage unit form comprising asolid or sterile liquid pharmaceutical carrier and from about 1 to 500milligrams of a compound of the formula: ##STR3## wherein: Formula Iincludes individual geometrical isomers and mixtures thereof,R₁ ishydrogen or alkoxy of 1 to 4 carbon atoms and R₂ and R₃ are each alkoxyof 1 to 4 carbon atoms; and R₄ and R₅ are each hydrogen or an alkanoylgroup containing from 1 to 20 carbon atoms with the proviso that one ofR₄ and R₅ is an alkanoyl group.
 2. The therapeutic composition of claim1 wherein at least one of R₄ and R₅ is acetyl.
 3. The therapeuticcomposition of claim 1 wherein at least one of R₄ and R₅ is propionyl.4. The therapeutic composition of claim 1 wherein at least one of R₄ andR₅ is pivalyl.
 5. The therapeutic composition of claim 1 wherein both R₄and R₅ are alkanoyl groups.
 6. The therapeutic composition of claim 1wherein both R₄ and R₅ are acetyl groups.
 7. The therapeutic compositionof claim 1 wherein the compound is N-mono or N,N-di-acetylated5-(3',4',5'-trimethoxybenzal) hydantoin.
 8. The therapeutic compositionof claim 1 wherein the compound is N-mono or N,N-di-acetylated5-(3',5'-dimethoxybenzal) hydantoin.
 9. The therapeutic composition ofclaim 1 wherein the compound is N-mono-acetylated5-(3',4'-dimethoxybenzal) hydantoin.
 10. The therapeutic composition ofclaim 1 wherein the compound is N,N-diacetylated5-(3',4'-dimethoxybenzal) hydantoin.
 11. The therapeutic composition ofclaim 1 wherein the compound is N-monoacetylated5-(2',4',5'-trimethoxybenzal) hydantoin.
 12. The therapeutic compositionof claim 1 wherein the compound is N,N-diacetylated5-(2',4',5'-trimethoxybenzal) hydantoin.
 13. A therapeutic compositionin dosage unit form for oral administration comprising tablets, pills,capsules, granules, powders or syrups containing a pharmaceuticalcarrier and from about 1 to 500 milligrams of a compound of the formula:##STR4## wherein: Formula I includes individual geometrical isomers andmixtures thereof,R₁ is hydrogen or alkoxy of 1 to 4 carbon atoms and R₂and R₃ are each alkoxy of 1 to 4 carbon atoms; and R₄ and R₅ are eachhydrogen or an alkanoyl group containing from 1 to 20 carbon atoms withthe proviso that one of R₄ and R₅ is an alkanoyl group.
 14. Atherapeutic composition for parenteral administration comprising asterile liquid pharmaceutical carrier containing from about 0.05 to0.10% of a compound of the formula; ##STR5## wherein: Formula I includesindividual geometrical isomers and mixtures thereof,R₁ is hydrogen oralkoxy of 1 to 4 carbon atoms and R₂ and R₃ are each alkoxy of 1 to 4carbon atoms; and R₄ and R₅ are each hydrogen or an alkanoyl groupcontaining from 1 to 20 carbon atoms with the proviso that one of R₄ andR₅ is an alkanoyl group.
 15. A therapeutic composition in dosage unitform comprising a pharmaceutically acceptable oil or water-oil emulsioncontaining from about 1 to 500 milligrams of a compound of the formula:##STR6## wherein: Formula I includes individual geometrical isomers andmixtures thereof,R₁ is hydrogen or alkoxy of 1 to 4 carbon atoms and R₂and R₃ are each alkoxy of 1 to 4 carbon atoms; and R₄ and R₅ are eachhydrogen or an alkanoyl group containing from 1 to 20 carbon atoms withthe proviso that one of R₄ and R₅ is an alkanoyl group.
 16. Atherapeutic composition comprising a saline solution containing fromabout 0.05 to 0.10% of a compound of the formula: ##STR7## wherein:Formula I includes individual geometrical isomers and mixturesthereof,R₁ is hydrogen or alkoxy of 1 to 4 carbon atoms and R₂ and R₃are each alkoxy of 1 to 4 carbon atoms; and R₄ and R₅ are each hydrogenor an alkanoyl group containing from 1 to 20 carbon atoms with theproviso that one of R₄ and R₅ is an alkanoyl group.